Secrets to a long and healthy life for your battery

PUBLISHED : Tuesday, 03 February, 2004, 12:00am
UPDATED : Tuesday, 03 February, 2004, 12:00am

What is the best way to treat my Apple iBook lithium ion battery? Should I keep it plugged into the wall even when it is fully charged or should I unplug it? And if unplugging basically means letting the battery go down, should I let it go down to absolutely dead or half dead before recharging?

I've researched these questions and everyone says something different. Some say that deep cycling shortens the battery's life span; others say it does not. But no one says whether leaving it plugged in while fully charged is bad. Mary Oey New York City

Nothing irritates more than a computer running out of battery life when there are no mains sockets in sight. An updated version of Richard III would have him looking for a battery to save his kingdom, not a horse.

Much has been said about batteries and, as you rightly point out, much of it is questionable.

People in the computer industry bemoan the slow progress of battery capacity compared with other aspects of technology. The problem is that batteries are not part of the electronics revolution but are still firmly in the world of chemistry.

Progress has been made in creating batteries that last longer, but the advances are still extremely small. A battery brick that lasted two hours 10 years ago, now can just about make it to six.

Although you ask about the iBook, most of what follows is true for any battery for a PC or Mac.

I spoke to some experts, including local computer dealers and people who work in the television business, where battery life is a matter of staying on air. These are people who take battery life seriously.

A healthy lithium ion battery should last longer than any other kind but there are things to be aware of.

Keeping the battery plugged into the mains should not be a problem as long as your computer knows that it is not meant to be charging it. This could be tricky because the icon on the screen may not accurately reflect what is going on. If you have any doubts about this and will be using the machine for long periods plugged into the mains, you may want to take the battery out.

The secret to lithium ion batteries is that, although they can be charged to last for many hours, they cannot be charged indefinitely. One expert said a lithium ion battery could be charged about 1,200 times. After that, it would begin to degrade. So, each time you begin a charge, you are slightly killing the battery.

Obviously, this has led to the idea that you should let the battery go down to as close as zero power before recharging it.

Once again, one must be careful here because letting it go totally flat can also be a bad thing. However, most batteries and personal computers have built-in mechanisms that prevent this.

In the end, though, the day will certainly come when you will need to buy a new battery.

If you travel extensively and think you'll use your battery a lot, you may want to get a second one.